Senior Security Engineer

Benefits

Parental leave

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Non-birth-parent leave

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Family-building benefits

• Fertility benefits: Not verified
• Adoption assistance: Not verified
• Surrogacy assistance: Not verified

Mental health support

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Relocation assistance

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Childcare support

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Learning budget

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Verification

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Salary

GBP 76K-101K From the posting source checked Jun 20, 2026

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Role

Role function

Security From the posting source checked Jun 20, 2026

Seniority

Senior From the posting source checked Jun 20, 2026

Schedule

Shift type

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Weekend work

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Company

Equity

Offered From the posting source checked Jun 20, 2026

Application

Cover letter

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Assessment

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Deadline

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Where they hire

State eligibility is not yet verified.

About this role

Senior Security Engineer United Kingdom Mattermost is the leading collaborative workflow platform for defense, intelligence, security, and critical infrastructure. Trusted by the U.S. Department of War and Fortune 500s, our platform runs on-premises and in private clouds, delivering secure messaging, file sharing, workflow automation, audio/screenshare, and project management-all with full data and operational control. Mattermost powers high-stakes workflows across mission planning, real-time, real-world operations, DevSecOps, incident response, and cyber defense-enabling secure collaboration from tactical edge and DDIL environments to enterprise HQ. Teams operate across web, desktop, and mobile, with embedded interoperability for Microsoft Teams, Outlook, and Microsoft 365. To learn more, visit www.mattermost.com Mattermost is the secure collaboration platform trusted by Global organizations. Our platform runs on-premises, cloud, and in air-gapped environments, enabling mission-critical workflows from the tactical edge to the enterprise HQ, where data sovereignty and operational security are non-negotiable. We are hiring a Senior Security Engineer to protect the people, infrastructure, and tooling that goes into building and hosting Mattermost. This is a hands-on, high-impact role at the intersection of enterprise security engineering, cloud information security, and AI-enabled threat response. Why Join Mattermost - Fully remote, globally distributed team | no commute, genuine flexibility - Be a key voice in shaping and delivering security strategy - Competitive salary, equity, and benefits with meaningful work attached The Role As a Senior Security Engineer, you will lead the design and implementation of security tooling, harden our cloud and IT infrastructure, and serve as a key responder to incidents. You will

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